1. Technical Field of the Invention
The present invention relates to novel cosmetic compositions for topical application, for the photoprotection of the skin and/or the hair against ultraviolet radiation (such compositions hereinafter simply designated "sunscreen" or "antisun" compositions), and to the use of same for the cosmetic applications indicated above.
This invention more especially relates to the aforesaid sunscreen/antisun compositions comprising, in a cosmetically acceptable support (vehicle, diluent or carrier) unique immixture of (a) at least one bis-hydroxyphenylbenzotriazole compound as a first screening agent and (b) as a second screening agent, at least one compound comprising at least two benzazolyl functional groups or at least one compound comprising at least one benzodiazolyl functional group. This admixture imparts enhanced sun protection factors to the subject compositions via an unexpected synergistic effect.
2. Description of the Prior Art
It is known to this art that light radiation with wavelengths from 280 nm to 400 nm promotes tanning of the human epidermis and that irradiation of wavelengths of from 280 nm to 320 nm, i.e., UV-B irradiation, causes skin burns and erythema which may be harmful to the development of a natural tan; this UV-B radiation should thus be screened from the skin.
It is also known to this art that UV-A radiation, of wavelengths from 320 to 400 nm, which tans the skin, also adversely affects it, in particular in the case of sensitive skin or of skin which is continually exposed to solar radiation. In particular, UV-A rays cause a loss of elasticity of the skin and the appearance of wrinkles, promoting a premature aging thereof. Such irradiation promotes triggering of the erythemal reaction or amplifies this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. It is thus desirable to also screen out UV-A radiation.
A wide variety of cosmetic compositions for the photoprotection of human skin (against UV-A and/or UV-B) are known to this art.
These sunscreen/antisun compositions are typically in the form of an emulsion of oil-in-water type (i.e., a cosmetically acceptable support comprising an aqueous dispersing continuous phase and an oily dispersed discontinuous phase) which contains, in varying concentrations, one or more conventional lipophilic and/or hydrophilic organic sunscreens capable of selectively absorbing the harmful or deleterious UV radiation, these screening agents (and the amounts thereof) being selected as a function of the desired protection factor (the protection factor (PF) being expressed mathematically by the ratio of the irradiation time required to reach the erythema-forming threshold with the UV screening agent, to the time required to attain the erythema-forming threshold without a UV screening agent).